Rational approach to quantitative sodium dodecyl sulfate capillary gel electrophoresis of monoclonal antibodies

Sodium dodecyl sulfate capillary gel electrophoresis has been used to separate and quantify murine monoclonal antibodies. The method uses a murine IgG, whose subclass differs from the analyte antibody, as an internal reference. The internal reference is chosen based on knowing that mouse IgG1 can be separated from mouse IgG2a or IgG2b. Good intra- and inter-day reproducibility [relative standard deviation (RSD)<2%] of peak-area ratio has been obtained. A calibration curve also demonstrates high linearity (R2=0.9999) of response for the analyte. The described method is highly suitable for accurate determination of the antibody concentration even if a capillary electrophoresis apparatus is unable to provide good injection reproducibility.